Characterization on three-dimensional surface topography of textured cold-rolled steel sheets

摘要

It is commonly accepted that the surface topography of cold-rolled steel sheet for automobile panels has great influence on its press performance and painted appearance. To achieve satisfactory press performance and painted appearance, steel sheet is generally produced with a textured as opposed to a smooth surface. The surface texture is transferred to the steel sheet during final cold rolling, in much the same way as newsprint from print rolls. The ways of formatting the rolls are usually by shot blast texturing (SBT), laser texturing (LT), electron beam texturing (EBT) or electrical discharge texturing (EDT). Due to the differences in the texturing technologies from traditional mechanical processing technology, the surface topography of textured steel sheet is deterministic-stochastic and has many functional properties. In this case the conventional 2D surface roughness parameters such as Ra cannot provide a satisfactory functional characterization of the surface topography of the steel sheet. In this paper seven 3D parameters are used to characterize 3D surface topography of cold rolled steel sheet from four major aspects, i.e. the amplitude, structure, function and texture. All these topographical features have a strong relation with the steel sheets' press performance during pressing and their painted appearance after painting. The surfaces of four different typical steel sheets are measured by a Talysurf 5 stylus instrument in this experiment. The characterizing parameters of the surface topography of these steel sheets are calculated and the topographical features of these steel sheets are analyzed and compared.